1. Field of the Invention
The present invention is directed to liquid crystal displays, and more particularly to a method of resizing a liquid crystal display without first removing the polarizer.
2. Description of the Related Art
Liquid crystal displays (LCDs) are well known in the electronic arts for displaying images and data to a user (e.g. avionics, computer displays, cellular telephones, etc.) A liquid crystal cell is typically provided with two glass substrates having thin transparent ITO (indium tin oxide) layers evaporated on the inner surfaces thereof (referred to herein as the TFT glass and the color filter glass, respectively). Polyimide layers (or any homogenous alignment material such as silane, evaporated silicon monoxide, etc.) are coated on top of the respective ITO layers for aligning the liquid crystal molecules within the cell. Thus, for a left-hand twisted cell, the polyimide layer on the bottom substrate is rubbed along the 0° direction (Cartesian coordinates), while the top polyimide layer is rubbed along the 90° direction (according to the right hand rule in Cartesian coordinates). The glass substrates are bonded together to form a cell using epoxy or thermoplastic material. Next, the cell is filled with liquid crystal by either vacuum filling or by a capillary method. After filling, the cell is sealed and uniform pressure is applied over the cell to improve the uniformity of the cell gap. Bottom and top polarizers are laminated with respective transmission directions perpendicular to the rub directions of the bottom and top polyimide layers. Finally, a reflective layer is deposited on the top polarizer.
Conventional LCDs are available in standard sizes that, in some cases, do not fit the intended application. For example, human factors and space limitations may dictate a smaller than conventional LCD be used for avionics display in the cockpit of an aircraft (military or civilian). Methods are known in the art for resizing LCDs to fit an intended application.
U.S. Pat. No. 6,204,906 (Tannas) discloses a method of changing the physical shape of an electronic display, wherein the display comprises a front plate, a back plate, and a perimeter seal spacing apart the plates, and wherein the image-generating medium is sealed in an area between the plates and within the borders of the perimeter seal. The method comprises cutting the display along desired dimensions, resulting in a target display portion and an excess display portion, thereby breaking the perimeter seal of the display. A seal is applied between the plates along an exposed edge of the target display portion, wherein the seal includes an adhesive having mechanical properties for preserving cell spacing between the front and back plates.
WO 99/19765 (Marconi Avionics (Holdings) Limited) sets forth a method of resizing an LCD having a liquid crystal sealed between first and second parallel transparent plates forming an operative area of the display. In its broadest aspect, the method comprises removing an excess region of the display by cutting through the first and second plates to isolate the excess region of the first and second plates and to expose cut edges along the operative areas of the first and second plates.
U.S. Pat. No. 6,509,949 (Lu et al) sets forth a method of resizing a liquid crystal display comprising the removal of any tape automated bonding strips (TABs) and flex circuits corresponding to undesired portions of the LCD. Any circuit boards, or portions thereof, corresponding to the undesired portion of the LCD are then cut and removed. The display panel is cut to remove a portion of the display panel corresponding to the undesired portion of the LCD and, finally, the cut edge of the display panel is sealed.
Each of the foregoing prior art LCD resizing methods also specifically includes removal of the polarizer before cutting, which adds to the processing costs and time required to resize the display. Also, the prior art is silent on any preferred approach to flex PCB (printed circuit board) cutting.